1. Field of the Invention
The present invention relates to an information processing device, a method of identifying an operation of a fingertip, and a program that identify an operation of a fingertip in contact with or in proximity to an operation surface based on an output of a sensor such as a touch pad that detects contact or proximity of an object in a plurality of positions on the operation surface.
2. Description of the Related Art
An input device such as a touch pad or a touch panel including a sensor that detects a contact position of an object, such as a finger or a pen, has been widespread as a man-machine interface of an information device, such as a notebook type PC, a tablet terminal, or a smartphone. Further, in recent years, in this type of input device, input devices corresponding to “multi-touch” in which a plurality of contact places can be detected have increased. In an input device using a multi-touch scheme, since an operation using one finger and an operation using a plurality of fingers can be identified, a variation of an input operation increases, and convenience improves in comparison with a case in which an input device is limited to single touch.
A multi-touch digitizer system that detects a contact position of a finger or the like using a two-dimensional sensor matrix that detects a change in capacitance between conductive lines orthogonal in a lattice form is described in Japanese Unexamined Patent Application Publication No. 2011-501261.
Incidentally, in an input device using a multi-touch scheme, when an operation is performed with one finger, other portions of a hand unintentionally come into contact with or are in proximity to a sensor, and an operation of a plurality of fingers may be erroneously recognized.
Japanese Unexamined Patent Application Publication No. 2011-501261 described above discloses a technology for determining that a potential fingertip touch area in proximity to a palm touch area having a great area is ineligible as a true fingertip touch area. Accordingly, when a palm unintentionally comes in contact with the sensor, it is possible to prevent a touch area having a small area that easily appears near the palm touch area from being erroneously determined to be the fingertip touch area.
However, not only the palm having a great area unintentionally come into contact with the sensor. For example, when a touch operation is performed with a tip of an index finger with a middle finger or a ring finger lightly bent, a joint part of the bent middle finger, ring finger, or the like may come into contact with the operation surface. A contact area of this joint part is much smaller than that of the palm. Accordingly, in the technology disclosed in Japanese Unexamined Patent Application Publication No. 2011-501261 described above, the joint part may be misrecognized as a true fingertip touch area instead of being recognized as a palm touch area.